Digester.



' may be introduced, andk while being intro- UNITED STATES Patented October 13, 1903.

PATENT OFFICE.

THOMAS w. MCEAELAND, ori-CHICAGO, ILLINOIS.

sPEcIFIcATIoN fming part of Lett-@repartent No. 741,530,l dated octber 13, 1903.-

Apputaipniiiea rebmr'y 3, `1902. :serai No. 92.262. (No moda Illinois, have invented certain new and useful Improvements` in Digesters, of which the fol-v Vlowingis afull, clearg'and exact specification.

My invention relates to that class of vdigesters employed for digesting or cooking fibrous substances-su ch as cotton-seed h ulls,

flax-stalks, hemp, wood, and other matterfrom which to produce paper-pulp; and my invention has for its primary object to pro-1 vide improved means whereby an energetic and positive defined circulation of the cookingliquorand fiber beingtreated maybe maintained during the cooking operation, whereby all particles ofthe fiber will be successively brought into intimate association with the cooking liquor at the `hottest part of` thedi-` gester and all cloggingor matting ofi-the material prevented. v

With these ends in-v'iew myinvention consists in certain features of novelty in the construction, combination, and arrangement of parts by which the said .objects and certain other objects hereinafter appearing are attained, all as fully described with reference t0 the accompanying drawing; and more particularly pointed out in the claims; Y

The said drawing illustrates a vertical sectional view of my improved digester.

l is a shell which may bev of cylindrical or any other suitable form',"but preferably vertically elongated and provided atits upper end with a cover 2, closing a charging-aperture 3, through which the fiber to be treated duced it is sprinkled, and thus intermittently commingled vwith the cooking liquor, by a spray from an annular spray-pipe 4, arranged at thefupper end of the shell and supplied when desired from a pipe 5, having valve 6 and connected to a discharge-pipe 7, leading from aypump 8, whose induction-pipe 9 is.

The bottomy of the shell.1 provided with a cone 11, which is ,secured to the sides and bottom of the shell and forms therewith an annular chamber 12, into which the cooking ,liquor finds its way through strainers constituted by perforations 13 at suitable inter- *Vals in the cone 1l, thus permitting the liquor to pass on tothe pump without danger ofclog'ging the pump with the ber.

. Suspended in the center of the shell 1 is a `flue 14, composed of an open-ended cylinder "or other suitable device, which is maintained in positionby a ring 15, supported from the topofv the shell by a number of` suspensionlrods 16, and-which Hue constitutes a passage' for the upward current of they cooking liquor and particles` of fiber or. material being treatend ofthe iue 14 to again fall into thepath of the ascending current when it strikes the sloping sides of the cone 11it being observed that the space between the lower end of the `iiue 14 and the cone is unobstructed, so as to reduce to the minimum any possibility of the fiber or material Vbridging at this point. In'order, however, that this lpassage may be kept absolutely open and free from clotted material, it' is continuously swept by an agi-- tator-arm 19, secured t0 the upper end of a vertical shaft 20, ljournaled at its upper end in spider 2Oa and whose lower end passes through suitable stuffing-box 2l in the lower end of Y 22 and is driven by sprocket 23 and chain 24 or other suitable means. This agitator-arm 19 may, if desired, be provided withspurs or fingers 25, suitably projected forreaching substantially all points of the passage between the cone and the flue.

The requisite heat for cooking the contents of the shell is supplied by a steam-coil 26,

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A end of the fine, whence it descends around the outer sides of the flue, where the liquor is cooler, and is caught by the contracted sides of the cone, and thus carried directly under the lower end of the line, where it is again carried upwardly by the ascending current therethrough. Whether the heat of the ascending current within the flue or the dynamic force of the current supplied by the pump through the bottom inlet 17 will be suflicient to throw the liquor and material over the upper end of the tine and cause the described circulation will of course depend upon the relative height of the flue and depth of the cooking liquor, and as this depth varies as the cooking operation proceeds it is important that the height of the iue be also capable of corresponding variation. The upper end of the flue, therefore, is provided with a telescopic section 29, which may be adjustably held in position by any suitable means. In the example of the invention shown in the drawing the upper end of this section 29 is provided with a pair of hooks 30, which are connected by chains 3l to a windlass 32, journaled in suitable bearings 33, secured to the suspension-rods 16, the windlass passing through stuffing-box 31k in the side of the shell and having a crank 35, whereby it may be manipulated for raising or lowering the telescopic section as the exigencies of the case may require. In order that the telescopic section 29 may rise and fall without interference from the coil-pipe 28, it is slotted on one side, as shown at 36.

When it is desired to discharge the contents of the digester, a gate-valve 37 in a pipe 38, leading from one branch of the Y 22, may be opened.

Having thus described my invention, what I claim as new therein, and desire to secure by Letters Patent, is-

1. In an apparatus for the purpose described, the combination of a shell, a perforated cone dividing the bottom of said shell into chamber 12, a flue suspended in said shell over the center of said cone, the space between the lower end of said flue and said cone being unobstructed and constituting a free passage for the material being treated in the shell, means for causing a circulation up wardly through said flue and downwardly between the flue and the shell and the flue and the cone, and' a pump connected with said chamber 12 and with the shell within said cone, substantially as set forth.

2. In an apparatus for the purpose described, the combination of a shell, the flue suspended in said shell, a perforated cone at the bottom of said shell under said flue, a revolving agitator below said flue and over the perforated cone for agitating the material between the lower end of the fine and the sides of the shell and the cone, and means for cansing a circulation of the material upwardly through the flue and downwardly around the outersides thereof, substantially as set forth.

3. In an apparatus for the purpose described, the combination of a shell, a liuc suspended therein, said shell having an outlet and an inlet in the bottom thereof, a spider bridging said inlet, a shaft passing downwardly through said inlet and journaled in said spider, means for revolving said shaft, and a laterally-projecting agitator-arm secured on the upper end of said shaft and sweeping the space between the lower end of said flue and the shell, substantially as set forth;

4. In an apparatus for the purpose described, the combination of a shell, a iiue suspended therein and having a telescopic section, and means for causing a circulation upwardly through said flue, substantially as set forth.

5. In an apparatus for the purpose described, the combination of a shell, a flue suspended therein and havinga telescopic section, exterior operating means connected with said telescopic section for adjusting it vertically, and means for causing an upward current through said fiue, substantially as set forth.

6. In an apparatus for the purpose described, the combination of a shell, a flue in said shell, the suspension-rod 16 for suspending said flue, a telescopic section on the upper end of said fine, the windlass 32 connected with said section for raising it, the bearings 33 for said windlass on said rods, eXterior operating means for said windlass and means for causing a circulation through said flue, substantially as set forth.

THOMAS W. MCFARLAND.

Vitnesses:

F. A. HOPKINS, W. D. (JBoss.

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